Changed Functions

set_error_handler() can now be called with NULL as an argument to reset the error handler.
When called with NULL, set_error_handler() and set_exception_handler() now return the previous error or exception handler, respectively.
The behaviour of pack() and unpack() with the "a" and "A" format codes has changed. Detailed notes on these changes are available.

MessageFormatter::format() and related functions now accept named arguments and mixed numeric and named arguments when PHP is linked to ICU 4.8 or later.
MessageFormatter::format() and related functions no longer error when an insufficient number of arguments have been provided. Instead, the placeholders will not be substituted.
MessageFormatter::format() and MessageFormatter::parse() are no longer limited to second precision when dealing with times.
IntlDateFormatter::__construct() and datefmt_create() now accept IntlTimeZone and DateTimeZone objects for the timezone argument, and IntlCalendar objects for the calendar argument. Furthermore, if the time zone is omitted and the calendar doesn't specify a time zone, PHP's default time zone from date_default_timezone_get() is now used instead of the default ICU time zone.
IntlDateFormatter::getCalendar() and datefmt_get_calendar() return false if the IntlDateFormatter object was created with an IntlCalendar instance instead of one of the IntlDateFormatter constants.
IntlDateFormatter::setCalendar() and datefmt_set_calendar() now accept IntlCalendar objects in addition to the IntlDateFormatter constants.
IntlDateFormatter::format() and datefmt_format() now accept IntlCalendar objects.